I don't think I would compose a letter at all...isn't that what the lawyer is for? Leave the dirty work to them, that is what they get paid for...and then if H confronts you just innocently state that you were advised not to for your own protection. If he still pushes direct him to the lawyer and tell him if he can convince the lawyer then you would "re-consider".
I still think he may have a longer term goal here...one where he secures a property in his name only, rights removed from you, and then he can let the home you have go and allow his credit to go with yours since he won't "need" his credit after the fact!
I think you should discuss this scenario with your lawyer...I have seen a lot of stuff done to a spouse, who while being advised, missed the white elephant in the middle of the room...lawyers can't always think of all the possibilities so mentioning this will at least cause thought to be given...and advice to fit it.
Then, it could be explained to H that if he wants to do this still he would have to agree that should he default on your home, the newly aquired home would then become legally yours!
This would ensure that he would not mess around with your credit, or his and his living plans!
